{-# LANGUAGE CPP #-} module Examples.Commands where import Data.List import Options.Applicative #if __GLASGOW_HASKELL__ <= 702 import Data.Monoid (<>) :: Monoid a => a -> a -> a (<>) = mappend #endif data Sample = Hello [String] | Goodbye deriving Show hello :: Parser Sample hello = Hello <$> many (argument str (metavar "TARGET...")) sample :: Parser Sample sample = subparser ( command "hello" (info hello (progDesc "Print greeting")) <> command "goodbye" (info (pure Goodbye) (progDesc "Say goodbye")) ) run :: Sample -> IO () run (Hello targets) = putStrLn $ "Hello, " ++ intercalate ", " targets ++ "!" run Goodbye = putStrLn "Goodbye." opts :: ParserInfo Sample opts = info (sample <**> helper) idm main :: IO () main = execParser opts >>= run